Figure 12. Imposed and induced modifications of the temporal patterns of ‘on’ and ‘off’ responses associated with S⁺ and S⁻.

This analysis was performed only for cells whose responses were significantly modified following the application of contiguous ‘on’ or ‘off’ pairings (thus excluding FDP protocols). A, imposed effects of contiguous S⁺ and S⁻ pairings on ‘on’ and ‘off’ responses. The histograms of response changes (‘during pairing’ minus ‘before pairing’), synchronized with the ‘on’ transition (left column) or the ‘off’ transition (right column), have been normalized relative to the mean count of each bin estimated by averaging responses before and during pairing (see Methods). A facilitation of ‘on’ and ‘off’ responses (upward histograms) was observed as expected during S⁺ pairings, whereas a depression was imposed during S⁻ pairings (downward histograms). B, induced effects of contiguous S⁺ and S⁻ pairings on ‘on’ and ‘off’ responses. The histograms of response changes (‘after pairing’ minus ‘before pairing’), synchronized with the ‘on’ or ‘off’ transition, have been normalized relative to the average count of each bin estimated by averaging responses before and after pairing (see Methods). Gains in visual responsiveness (upward histograms) were induced for both ‘on’ and ‘off’ transitions of the stimulus following their respective pairing with a ‘high’ level of activity (S⁺). Losses of responsiveness (downward histograms) were induced for ‘on’ and ‘off’ characteristics associated with a reduced level of activity (S⁻). Both the early and late components of the response (up to 800-1000 ms after an ‘on’-S⁺ pairing) could be modified by the pairing procedure.